Signaling pathways such as the MAP kinase pathway are used in many different tissues throughout metazoan development to control important cell fate decisions. Misinterpretation of a signal by a cell can lead to cancer or developmental defects. However, the mechanisms by which a signal directs downstream effectors to generate the ultimate fate of the cell remain largely mysterious. The long-term objective of this proposal is to gain a comprehensive knowledge of how the information from a cytoplasmic signal such as MAP kinase is interpreted through altered target gene expression to produce a specific cell fate. These studies focus on MAP kinase regulation of meiotic progression in the Caenorhabditis elegans germ line. Because MAP kinase mediates meiotic progression in many species, the results obtained from these studies will potentially be broadly applicable. By taking functional genomics approaches to identify genes acting downstream of the MAP kinase signaling pathway, followed by classical molecular analysis of key effeetors, comprehensive knowledge of the genetic and biochemical network responding to MAP kinase in a particular tissue will be attained. [unreadable] [unreadable] Specifically, DNA microarrays will be used to identify candidate transcriptional target genes downstream of MAP kinase signaling in the C. elegans germ line. The cis-acting regulatory sites in those genes will be defined through sequence identification algorithms and tested for MAP kinase responsiveness through transgenic analysis. Candidate immediate-early genes encoding transcription factors will then be examined for binding to the cis-acting sites identified in the target genes. The requirement for these downstream effectors, whether transcription factor or transcription target, in mediating MAP kinase dependent meiotic progression in vivo will be assessed using RNA-mediated interference and genetic analysis. Together these experiments should build toward a comprehensive understanding of the mechanisms used to produce a specific cell fate in response to a generally used signaling pathway.